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| STUDY ON THE ELECTRO–REFINING SILICON IN MOLTEN SALT CaCl2–NaCl–CaO |
| WANG Shulan, CHEN Xiaoyun |
| School of Sciences, Northeastern University, Shenyang 110004 |
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Cite this article:
WANG Shulan CHEN Xiaoyun. STUDY ON THE ELECTRO–REFINING SILICON IN MOLTEN SALT CaCl2–NaCl–CaO. Acta Metall Sin, 2012, 48(2): 183-186.
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Abstract Use Cu–31Si alloy (31mol% Si) prepared by inductive melting metallurgical grade silicon as anode and molybdenum as cathode and reference electrode, the cathodic behavior of molten salt 81CaCl2–8.0 NaCl–8.5CaO–2.5Si (Mole fraction, %) at 1173 K was studied by means of cyclic voltammetry and chronopotentiometry, and the reduction steps of silicon from the molten salt were discussed. The electro–refining of silicon was performed in the two electrode system under the voltage of −0.2 V. SEM, EDS and inductively coupled plasma atomic emission spectrometry (ICPAES) technologies were used to analyze and characterize the morphology and composition of the deposited silicon. Polycrystalline silicon was obtained after the electro–refining. Main impurity in the metallurgical grade silicon are greatly decreased. Especially boron and phosphorous which are very harmful to solar cell grade silicon were greatly removed. The contents of boron and phosphorous are decreased from 42×10−6 and 25×10−6 to 4.5×10−6 and 8.2×10−6, respectively. The current efficiency of the electro–refining process is 84.4%.
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Received: 30 August 2011
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| Fund: Supported by National Natural Science Foundation of China (No.51154002) |
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